Former President Bill Clinton rocked the Colorado Democratic Senate primary Tuesday, endorsing former state House Speaker Andrew Romanoff's challenge to appointed Sen. Michael Bennet.

In a message calling Romanoff a politician who will "stand up to special interests and fight for working families," Clinton praised the insurgent liberal's long work building the Colorado Democratic Party: " He worked harder than anyone in Colorado to put Democrats in positions of power — and to use that power to benefit every single citizen. Andrew led the effort to win a majority in the Colorado House of Representatives for the first time in 30 years and to keep that majority for the first time in more than 40 years."

Romanoff is the first primary challenger to win support from Clinton, who helped Arkansas Sen. Blanche Lincoln turn back a challenge last month from Lt. Gov. Bill Halter, a former official in his administration.

And Clinton did not endorse Pennsylvania Rep. Joe Sestak's campaign against Sen. Arlen Specter — and even worked with the White House to suggest Sestak pursue other jobs in Washington — despite his longstanding affinity for the former admiral who served in his White House.

"We need Andrew's leadership in Washington — especially now, when so many Americans are losing so much," Clinton said in his endorsement of Romanoff. "'It is not enough,' as Andrew put it at the Colorado Democratic Assembly last month, 'to put a president of real talent and vision and leadership in the White House if the same qualities are not matched at the other end of Pennsylvania Avenue.'"

An automated SurveyUSA poll taken earlier this month showed Romanoff with a steep hill to climb against Bennet, the former Denver schools chief who was appointed to his seat after Ken Salazar became Interior secretary. Bennet took 52 percent support in the poll, compared with 36 percent for Romanoff.